Jump to content

Beware of Memory Leak from abusing undocumented With...EndWith syntax on DllStructs


Recommended Posts

If a function returns a struct member while inside a With statement, the struct gets a new instance that do not get cleaned up.

 

HotKeySet('{esc}',quit)
GUICreate("")
GUISetState()
Local $text
While 1
    $text = state()
    Sleep(10) ; don't remove this, or your RAM will blow up instantly
WEnd

Func state()
     Local Static $struct = DllStructCreate('wchar string[1024]')
     With $struct
          Return .string
     EndWith
EndFunc

Func quit()
     exit
EndFunc

 

 

Tested on 3.3.16.0

Edited by AutoXenon
Link to post
Share on other sites
  • AutoXenon changed the title to Beware of abusing undocumented With...EndWith syntax on DllStructs

Hi AutoXenon

Could it be because the expression you used in your script isn't an object type expression ?

Your script :

With $struct
    ...

ConsoleWrite(VarGetType($struct) & @crlf)
DLLStruct

AutoIt help file, topic With...EndWith

Parameters
expression    Must be an object type expression


Help file example :

With $oExcel.activesheet
    ...

ConsoleWrite(VarGetType($oExcel.activesheet) & @crlf)
Object

 

Link to post
Share on other sites

Yes, hence my thread title. It's not meant to be used on DllStructs, so I'm aware of the perils of treading on undocumented grounds. This topic is meant to point out specific instances of where such unintended usage might go wrong.

Link to post
Share on other sites

This is a defect in autoit3.exe and you should open a ticket about it.

autoit3.exe correctly barks when With is used on, e.g. a string while it doesn't for DllStruct.

Local $m[]
Local $b[3]
Local $a = [ _
    DllStructCreate('wchar string[1024]'), _
 _  ;   $m, _
 _  ;   $b, _
 _  ;   123, _
 _  ;   "abc", _
 _  ;   Binary(123), _
 _  ;   Ptr(123456), _
 _  ;   True, _
 _  ;   Null _
    ObjCreate("shell.application") _
]
For $v In $a
    ConsoleWrite(VarGetType($v) & @TAB)
    With $v
        ConsoleWrite("passed" & @LF)
    EndWith
Next

Uncomment the various datatypes to check by yourself.

This wonderful site allows debugging and testing regular expressions (many flavors available). An absolute must have in your bookmarks.
Another excellent RegExp tutorial. Don't forget downloading your copy of up-to-date pcretest.exe and pcregrep.exe here
RegExp tutorial: enough to get started
PCRE v8.33 regexp documentation latest available release and currently implemented in AutoIt beta.

SQLitespeed is another feature-rich premier SQLite manager (includes import/export). Well worth a try.
SQLite Expert (freeware Personal Edition or payware Pro version) is a very useful SQLite database manager.
An excellent eBook covering almost every aspect of SQLite3: a must-read for anyone doing serious work.
SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
A work-in-progress SQLite3 tutorial. Don't miss other LxyzTHW pages!
SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

Link to post
Share on other sites

Created ticket #3925

This wonderful site allows debugging and testing regular expressions (many flavors available). An absolute must have in your bookmarks.
Another excellent RegExp tutorial. Don't forget downloading your copy of up-to-date pcretest.exe and pcregrep.exe here
RegExp tutorial: enough to get started
PCRE v8.33 regexp documentation latest available release and currently implemented in AutoIt beta.

SQLitespeed is another feature-rich premier SQLite manager (includes import/export). Well worth a try.
SQLite Expert (freeware Personal Edition or payware Pro version) is a very useful SQLite database manager.
An excellent eBook covering almost every aspect of SQLite3: a must-read for anyone doing serious work.
SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
A work-in-progress SQLite3 tutorial. Don't miss other LxyzTHW pages!
SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

Link to post
Share on other sites
  • AutoXenon changed the title to Beware of Memory Leak from abusing undocumented With...EndWith syntax on DllStructs

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...